Vehicle seats in two-door, or coupe style, vehicles are hinged to permit access by passengers to the back seat of the vehicle by pivoting the front seat back forward. Such vehicle seats include a latch mechanism which prevents pivoting the seat back at other times. Manual latches prevent pivoting the vehicle seat back except when the manual latch is released. A more convenient latch mechanism is an inertia latch which locks the seat back hinge upon application of inertial force when the vehicle decelerates rapidly.
One example of an inertia seat back lock is disclosed in U.S. Pat. No. 4,438,974 to Kresky, et al. The Kresky device is directed to a specialized inertia pendulum which prevents lock-up when a car is parked in a nose-down position. It is considered desirable to provide more positive control of the positioning of the seat back in response to deceleration. A second pendulum has been proposed to reduce the pre-lock travel. This approach has been adopted on some car models. By providing the second pendulum, the already excessive number of parts required by the Kresky design is further increased. Adding parts to a seat back hinge inertia lock is undesirable as it adds cost to the assembly.
Another inertial lock for a vehicle seat is disclosed in U.S. Pat. No. 4,225,177 to Kluting, wherein a pinion gear is shifted forward in a slot to engage a locking member located adjacent to the slot. The design disclosed in Kluting is a relatively complicated structure that requires difficult assembly and operational requirements. The number of parts also affects the weight of the tilt lock mechanism. Critical weight reduction standards currently imposed on automotive designs pose an important constraint which must be addressed in seat back tilt lock mechanisms.
These and other problems encountered by the prior art are solved by this invention as summarized below.